title: Death receptor-induced activation of the Chk2- and histone H2AX-associated DNA damage response pathways.
abstract: TRAIL is an endogenous death receptor ligand also used therapeutically because of its selective proapoptotic activity in cancer cells. In the present study, we examined chromatin alterations induced by TRAIL and show that TRAIL induces a rapid activation of DNA damage response (DDR) pathways with histone H2AX, Chk2, ATM, and DNA-PK phosphorylations. Within 1 h of TRAIL exposure, immunofluorescence confocal microscopy revealed gamma-H2AX peripheral nuclear staining (gamma-H2AX ring) colocalizing with phosphorylated/activated Chk2, ATM, and DNA-PK inside heterochromatin regions. The marginal distribution of DDR proteins in early apoptotic cells is remarkably different from the focal staining seen after DNA damage. TRAIL-induced DDR was suppressed upon caspase inhibition or Bax inactivation, demonstrating that the DDR activated by TRAIL is downstream from the mitochondrial death pathway. H2AX phosphorylation was dependent on DNA-PK, while Chk2 phosphorylation was dependent on both ATM and DNA-PK. Downregulation of Chk2 decreased TRAIL-induced cell detachment; delayed the activation of caspases 2, 3, 8, and 9; and reduced TRAIL-induced cell killing. Together, our findings suggest that nuclear activation of Chk2 by TRAIL acts as a positive feedback loop involving the mitochondrion-dependent activation of caspases, independently of p53.
authors.affiliation: Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-4255, USA.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Solier
authors.forename: Olivier
authors.initials: O
authors.lastname: Sordet
authors.forename: Kurt W
authors.initials: KW
authors.lastname: Kohn
authors.forename: Yves
authors.initials: Y
authors.lastname: Pommier
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D064007:Ataxia Telangiectasia Mutated Proteins; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D051747:DNA-Activated Protein Kinase / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D053218:Receptors, Death Domain / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; D009687:Nuclear Proteins; D053218:Receptors, Death Domain; D053221:TNF-Related Apoptosis-Inducing Ligand; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C578634:CHEK2 protein, human; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D020169:Caspases